Which hormone influences the reabsorption of water in the collecting ducts of the nephron?
Antidiuretic hormone (ADH)
Aldosterone
Erythropoietin
Renin
The Correct Answer is A
A. Antidiuretic hormone (ADH): ADH (released from the posterior pituitary) specifically makes the collecting ducts more permeable to water, allowing it to be reabsorbed back into the blood.
B. Aldosterone: Aldosterone primarily causes the reabsorption of sodium, and water follows the sodium. ADH acts directly on water channels (aquaporins).
C. Erythropoietin: This hormone stimulates the bone marrow to produce red blood cells.
D. Renin: Renin is an enzyme that starts a hormonal cascade; it does not directly reabsorb water itself.
Nursing Test Bank
Naxlex Comprehensive Predictor Exams
Related Questions
Correct Answer is D
Explanation
A. By increasing urine production: Increased urine production would lower blood volume and further decrease blood pressure.
B. By producing erythropoietin: Erythropoietin is released in response to low oxygen (hypoxia), not specifically low blood pressure.
C. By excreting more sodium: Excreting sodium causes water loss, which would lower blood pressure. The kidneys actually retain sodium to raise blood pressure.
D. By releasing renin to activate the renin-angiotensin-aldosterone system: When blood pressure drops, the juxtaglomerular cells in the kidney release renin. This triggers a cascade that results in vasoconstriction and salt/water retention to increase blood pressure.
Correct Answer is B
Explanation
A. Muscle weakness: This is more common in hypercalcemia or hypokalemia.
B. Chvostek's sign: A serum calcium of 7.5 mg/dL is low (normal is 9–10.5 mg/dL). Hypocalcemia causes neuromuscular irritability. Chvostek’s sign (facial twitching when the facial nerve is tapped) is a classic finding.
C. Constipation: Constipation is a sign of hypercalcemia. Hypocalcemia often causes increased GI motility (diarrhea).
D. Hypertension: Hypocalcemia is more likely to be associated with hypotension and cardiac arrhythmias.
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